JPH0489252A - Manufacture of laminate - Google Patents

Abstract

PURPOSE:To obtain the laminate without appearance-defect, while open air does not flow into a heating furnace by using the heating function in which air curtains are provided at the inlet and the outlet for the furnace. CONSTITUTION:The impregnated laminate 1 to pass through a heating furnace enters the furnace 2 from its inlet 3 and is heated at the state where it is supported on a supporting roll and comes out from its outlet 5. Air curtains are respectively provided above and below the inlet 3 and the outlet 5 by the device 6 for the air curtain, whereby from the inlet 3 and the outlet 5, open air is prevented from flowing into. A number of the vent 7 for removing volatile matter and the feeding ports 8 of heated air for feeding open air are respectively provided in the furnace 2. A part of the heated air containing volatile matter sucked from the 7 is vented through an exhausting pipe 7'. The residual heated air flows together with open air, and is heated in an air-heating furnace 9, and then is fed in the heating furnace from a heated air-feeding port 8 through a heated air-feeding pipe 8'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved method of manufacturing a laminated board suitable for printed circuit boards used particularly in electrical and electronic equipment.

[Prior Art] Laminated boards are widely used as the main body of printed circuit boards used in electrical and electronic devices.

One of the manufacturing methods for this laminate is to stack a predetermined number of long resin-impregnated base materials such as glass cloth with a thermosetting resin, and to attach a long metal plate to one or both sides of the long resin-impregnated base materials. Obtain an impregnated laminate by laminating foil or cover film,
A continuous laminate manufacturing method in which this is cured in a heating furnace, or the impregnated resin is precured by preheating in a heating furnace, and then the precured resin is formed by heating and pressure molding using a double belt press or the like. Methods for manufacturing laminates that are cured are known.

In this method of manufacturing laminates, when a long impregnated laminate passes through a heating furnace, flammable volatile substances volatilize from both ends of the impregnated laminate. Exhausting things to the outside.

[Problem to be solved by the invention]

However, when a long impregnated laminate passes through a heating furnace that is evacuated in this way, external air flows into the furnace through the upper and lower surfaces of the impregnated laminate through the inlet and outlet openings of the heating furnace. As a result, the thermal expansion of the metal foil and cover film used as the covering material of the impregnated laminate does not occur uniformly, and as a result, the temperature in the impregnated laminate is uneven. There is a problem that uniform tension cannot be applied to the coating material, and the impregnated laminate is prone to wrinkles, undulations, etc., and appearance defects such as fine striped patterns are likely to occur on the surface of the laminate.

[Means to solve the problem]

As a result of intensive research in order to solve such problems, the present inventors found that it is possible to blow air from above and/or below the laminate at the inlet and/or outlet of the heating furnace, that is, to reduce the population and/or By providing an air curtain at the outlet, the amount of external air flowing in from the inlet and/or outlet of the heating furnace is reduced, the temperature in the furnace near the inlet and/or outlet is uniform, and the resulting laminate is free from wrinkles. The present invention was completed based on the discovery that waving is less likely to occur.

That is, in the present invention, an impregnated laminate formed by laminating long thermosetting resin-impregnated substrates and laminating a long metal foil or cover film on one or both sides thereof is vaporized in a heating furnace. Provided is a method for manufacturing a laminate, which includes a step of continuously heating materials while evacuating the material, and the method uses a heating furnace provided with an air curtain at the inlet and/or outlet as the heating furnace. It is something.

The present invention will be explained in detail below.

The thermosetting resin-impregnated base material in the present invention is a base material impregnated with a liquid thermosetting resin, and the liquid resin is not particularly limited and may be dissolved in a solvent, but it may contain a solvent. Liquid thermosetting resins (excluding reactive diluents such as polymerizable vinyl monomers) are preferred, and representative examples thereof include epoxy resins, unsaturated polyester resins, epoxy vinyl ester resins, and diallyl phosphate resins.

Typical examples of the base material for the thermosetting resin-impregnated base material include kraft paper, linter paper, glass cloth, glass nonwoven fabric, etc., but the present invention is not limited to these.

The metal foil used on one or both sides of the thermosetting resin-impregnated base material is typically an electrolytic or rolled copper foil with a thickness of 100 μm or less, and other materials such as aluminum foil may also be used.

Further, examples of the cover film include polyester film, polyimide film, and the like.

The thermosetting resin-impregnated base material can be produced by impregnating the base material with the resin using a conventionally known method. These thermosetting resin-impregnated base materials are manufactured as continuous long products, and after stacking multiple sheets and adjusting the resin content to a predetermined value as necessary, the above-mentioned metal foil is coated on one or both sides. Alternatively, a cover film is laminated to obtain a continuous long impregnated laminate.

This impregnated laminate is heated to pre-cure or harden the impregnated resin, and the heating furnace can be, for example, hot air heating, infrared heating (including far infrared heating and near infrared heating).
, high frequency heating, etc. are used, and these can also be used in combination.

In addition, as the heating furnace, a heating furnace is used that has the function of exhausting flammable volatiles that volatilize from both ends of the impregnated laminate by heating, and is equipped with an air curtain at the inlet and/or outlet. Among these, it is preferable to supply heated external air into the heating furnace from a portion other than the entrance and exit of the impregnated laminate of the heating furnace.

As an air curtain, for example, air is blown in a direction substantially perpendicular to the surface of the impregnated laminate from above and/or below the opening of the inlet and/or outlet, and the width of the air curtain is the same as that of the inlet and/or outlet. Examples include those that are larger than the width of the outlet opening.

Further, the temperature of the air to be blown is preferably lower than the air temperature inside the heating furnace and higher than the outside air temperature.
Above all, +0°C to -50° relative to the air temperature inside the heating furnace.
A range of C is particularly preferred.

An example of a heating furnace used in the present invention will be specifically explained below with reference to the drawings.

FIG. 1 is a sectional view conceptually showing a heating furnace used in the present invention. 2 is an impregnated laminate that passes through the heating furnace, enters through the inlet 3 of the heating furnace 2, is heated while being supported by support rolls 4, and comes out through the outlet 5. Air curtains are provided above and below the inlet 3 and outlet 5 by air curtain devices 6, respectively, to prevent outside air from flowing in from the inlet 3 and outlet 5.

Inside the heating furnace 2, there are provided a large number of exhaust lowers for removing volatile matter and a number of heated air supply ports 8 for supplying outside air, and the heated air containing volatile matter sucked from the exhaust lower is A part of the air is discharged to the outside through the exhaust pipe 7', and the rest is heated by joining with outside air in the air heater 9.
The heated air is supplied into the heating furnace from the heated air supply port 8 through the heated air supply pipe 8'.

The impregnated laminate used in the present invention can be cured in the above-mentioned heating furnace under no pressure; (2) precured under no pressure; then cured using heating and pressing means such as a double belt press; It is cured to form a laminate, and if necessary, it is post-cured.

The precuring or curing conditions are not particularly limited, but the temperature in the heating furnace is usually 60 to 200°C.
0~200°C 11~50kg/Cd.

In the curing method (2), the degree of pre-curing of the impregnated laminate in the heating furnace is extremely important; if the degree of pre-curing is too low, excessive flow of resin will occur during the subsequent heating and pressure forming, and the thickness of the laminate will increase. Accuracy decreases, and if the degree of precuring is too high, it is not possible to ensure an appropriate amount of resin flowing out during molding, which tends to cause voids in the laminate and scratches on the surface. Therefore, in method (2), temperature control of the heating furnace is important, and it is particularly preferable to employ the heating method of the present invention.

〔Example〕

Next, the present invention will be explained in detail.

In addition, parts indicate parts by weight, and % indicates weight %. Moreover, unless otherwise specified, glass cloth with a thickness of 0.18 mm was used in all cases.

Example 1 Epoxy resin with epoxy equivalent of 190 obtained by reaction of bisphenol A and epichlorohydrin 16.9
26.5 parts of an epoxy resin with an epoxy equivalent of 370 obtained by the reaction of tetrabromobisphenol A and epichlorohydrin, 26.6 parts of methyltetrahydrophthalic anhydride, 0.7 parts of benzyldimethylamine,
30 parts of an epoxy vinyl ester resin consisting of methacrylate (60%) of an epoxy resin with an epoxy equivalent of 370 obtained by the reaction of tetrabromobisphenol A and epichlorohydrin and styrene monomer (40%) and "Perhexa 3M" (Japan) Polymerization initiator made of oil and fat ■)
0.6 parts were mixed to prepare a solvent-free liquid thermosetting resin at room temperature.

This resin is impregnated into each of eight continuous glass cloths each having a width of 1020 wm so that the weight ratio of resin to glass cloth is 43:57. Eight resin-impregnated substrates were stacked together, and electrolytic copper foils having a thickness of 35 μm were bonded to both sides of the stack to obtain an impregnated laminate.

Next, this impregnated laminate was precured by passing it through the heating furnace shown in Fig. 1 (furnace temperature 110°C, heating air temperature 110°C, air curtain air temperature 80°C) for 5 minutes. Thereafter, it was heated and pressure-molded for 10 minutes at a pressure of 20 kg/c11I using a double belt press at 170°C, and cut into a length of 1000 wm to obtain 20 laminates.

The surface of the impregnated laminate was observed after leaving the heating furnace and while being conveyed to the double-held press, but no wrinkles, waving, etc. were observed. The surfaces of the 20 laminates obtained were also observed, and no defects in appearance were observed.

Comparative Example 1 Twenty laminates having a length of 1000 wm were obtained in the same manner as in Example 1 except that no air curtain was provided.

When the surface of the impregnated laminate was observed after leaving the heating furnace and being conveyed to the double belt press, wrinkles were confirmed.

In addition, fine striped appearance defects were observed in 12 of the 20 laminates obtained.

Example 2 Twenty laminates having a body length of 1000 mm were obtained in the same manner as in Example 1 except that the air temperature of the air curtain was changed to 40°C.

The surface of the impregnated laminate was observed after leaving the heating furnace and while being conveyed to the double-held press, but no wrinkles, waving, etc. were observed. The surfaces of the 20 laminates obtained were also observed, and no defects in appearance were observed.

〔Effect of the invention〕

According to the manufacturing method of the present invention, there is no inflow of outside air into the heating furnace, and a laminate with no appearance defects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a heating furnace used in the manufacturing method of the present invention. Note that the arrow indicates the direction of travel of the air or impregnated laminate. impregnated laminate, 2: heating furnace, 3: heating furnace inlet, 4: support roll, 5: heating furnace outlet, 6: air curtain device,
7: Exhaust port, 7': Exhaust pipe, 8: Heated air supply port, 8
': Heated air supply pipe, 9: Air heater.

Claims (1)

[Scope of Claims] 1. An impregnated laminate formed by laminating long thermosetting resin-impregnated substrates and laminating a long metal foil or cover film on one or both sides of the impregnated laminate is heated in a heating furnace. A method for manufacturing a laminate, which includes a step of continuously heating while exhausting volatile matter inside the laminate, which is characterized by using a heating furnace provided with an air curtain at the inlet and/or outlet as the heating furnace. . 2. The manufacturing method according to claim 1, wherein the air temperature of the air curtain is lower than the air temperature in the heating furnace and higher than the outside air temperature. 3. The manufacturing method according to claim 1 or 2, wherein heated air is supplied into the heating furnace at the same time as the volatile matter in the heating furnace is exhausted.